When it comes to decorating a dining room, the scheme will depend on several factors, such as whether it is a separate room or part of another, the existing furniture, the available light and the mood you are trying to create. Your choice of colour or theme could be inspired by your china or curtains - or maybe you need a neutral backdrop for stronger accent colours or interesting furniture. Red is a traditional colour for dining rooms and it does promote an intimate atmosphere, but it can be difficult to live with all the time and is best reserved for separate dining rooms.
Whatever colour combination or theme you choose, stick to it as closely as possible - too many styles and colours can create a cluttered look and will feel claustrophobic.
Seating
It is difficult to estimate how many people you can seat around a table. For a start, it depends on how friendly they want to get, but as a rule 60 cm per person is a good guide. If your chairs have arms, about the width of a pair of crossed arms - or 70 cm by a depth of 35 cm - is adequate for each place setting. Something else to bear in mind when seating people is the position of the table legs. Most of us have spent at least one uncomfortable meal with our legs straddling the table leg.
If you are trying to find chairs for a table you already own, take the height of the table with you when you go shopping. Chairs with arms should fit underneath the table for comfort and to save space. Try to allow 30 cm between the chair seat and the tabletop.
Setting a table
- Most dining is fairly casual these days and when it comes to setting a table for dinner there are no strict rules.
- Set places so that guests are evenly spaced around the table, trying to give them a minimum of 60 cm each.
- Lay cutlery according to the order of eating. The first cutlery to be used should be on the outside of the setting, so that you start at the outside and work your way in. Knives (with the blade facing the plate) and spoons go on the right of each place setting; forks on the left.
Glasses stand on the right above the knives and spoons. Use a wide goblet for red wine or water, a small wine glass for white wine and a smaller version yet for sherry or liqueurs. If you are only using one glass, a stemmed goblet will suffice.
The side plate should be on the left of the place setting and to the left of the cutlery, with the napkin on top of it.
Special Occasions
Decorating a table for dinner is the icing on the cake. Take time to plan what you are going to do and match it to the occasion.
Keep to a theme and follow it through to the china, cutlery, napkins and candles. Be creative: outline each place in ivy; put a fresh flower on each plate; tie up cutlery with ribbon; write out the menu and place cards on handmade paper.
Your theme could be a colour or a birthday. Try painting glasses either to match china or with the name or favourite thing of the birthday person. Use cotton sheeting instead of a tablecloth and dye or paint it. It is cheap enough to use for one special occasion.
A centrepiece can be matched to the occasion. Keep it simple and effective: floating candles and flower heads in a decorative bowl of water; a small group of flowers displayed in tin cans; an arrangement of candles of different heights; a pile of presents; a bowl of fruit to be eaten for dessert. Keep the centre-piece low so that guests can talk easily to each other over the top of it.
For a children's party buy a block of sugar paper and use the sheets as table mats; cover the table with a paper table-cloth, give them crayons and let them draw; tie brightly coloured balloons to the backs of chairs and let them take them home afterwards.
Tablecloths and napkins
Unless you want it to be floor length, a tablecloth should have an all-round drop of 25-30 cm so that it falls a little below lap level and your guests do not get tangled up in it. To a certain degree, a cloth will protect the table, but a felt table pad underneath allows you to put warmed plates and dishes safely on the cloth without marking the table.
Table felt is available from department stores, or look through the classified ads in home magazines for mail-order companies who will cut it to size to fit your table.
With so many pretty paper napkins available why bother with the fabric variety? They provide an opportunity to dress the table and create a little theme on a plate. Be imaginative and use twisted ivy, ribbon, parcel tags, dried flower heads, raffia, beads, copper garden tags and handwritten cards. Personalize each napkin for your guests.
For birthday meals, a little present attached to the napkin with ribbon is a nice touch; at Christmas, tie baubles with curling ribbon. There are loads of things you can do...
Fabric napkins do not need to be expensive. Cut them from remnants to match colour schemes, or make each one different. Scour the remnant bins in shops for unusual fabrics at bargain prices. Dress fabrics are ideal for making napkins as they are designed to with stand regular washing. If you use furnishing fabrics, wash them first to remove any dressing or special finish.
Tips: The simplest decorations are the most effective. Floating candles and a cut flower head in a bowl of coloured water look stunning in the centre of the table.
Dining areas as part of another room
Most dining areas are borrowed from another room, usually the kitchen or living room, but a dining area in a large hall or conservatory is not unusual. New houses are often built with just one room downstairs which has to double as both the living and dining area. So how do you decorate a room that has to serve more than one purpose?
- Create different moods by using lighting and furniture to highlight separate areas of the room while keeping the same colour throughout. Freestanding open shelves can divide a dining area from a sitting area without blocking any light and will provide useful storage space for both rooms. Two large rugs on a wooden floor can contain dining and sitting space within their boundaries.
- Another way to create a separate dining area is by using a moveable physical barrier such as a suspended screen to isolate a kitchen from its storage area or muslin on a curtain track. A re-standing screen will partially separate the table to give the dining area an intimate feel, and can be folded back against the wall when not in use.
- The space under the stairs is often under-used, yet this alcove can make a cosy dining area in a small house. Shelved, it will also provide valuable storage space for crockery and glassware. Another often-forgotten space for eating is the hall. Some older houses and flats have enormous hallways that will easily accommodate a large dining table and chairs. Such an arrangement could create a wonderful entrance to any property.
Many people decide to build a conservatory to give themselves an extra room, but if there is not a separate dining room this would be an ideal opportunity to create one. Conservatories are lovely to eat in and by their very nature have views over the garden and an intimate atmosphere when the sun goes down.
Sunday, September 16, 2007
Friday, September 14, 2007
Acrylic Glazing
Acrylic is light, easy to cut, and has more impact resistance than glass, though it scratches easily and has a high rate of expansion. Double-skin acrylic sheets are translucent, and the diffuse light is good for plants. Designer Valerie Walsh thermoforms these sheets into curved roof sections for custom sunspaces.
Commonplace now as the stuff of automobile lights, bank security window, gas-station signs, camera and contact lenses, TV screens, and even paint, blankets and carpets, acrylic plastic has been around a long time. Although development of this highly elastic substance began back in the 19th century, it was not until the 1930s that chemical firms first began producing commercial quantities of acrylic, which can be manufactured as a liquid, as fibres or in sheets. It took World War II, when the War Department started testing and using acrylic extensively in aircraft, to push the technology into the applications familiar to us today.
The larger family of plastic glazing materials has been closely scrutinized over the last decade by solar designers and builders searching for the least expensive material for collectors, greenhouses, windows, skylights and water storage. Most plastic glazings are flexible, light-weight, impact-resistant and light-diffusing. Acrylic stands out because it will not degrade or yellow in ultraviolet light. Along with high clarity and an impact resistance of 15 to 30 times greater than that of glass, acrylic offers a lifetime gauged at 20 years.
Given a burning rate of Class II in the codes, acrylic burns very rapidly, but does not smoke or produce gases more toxic than those produced by wood or paper. The ignition temperature is higher than that of most woods, but acrylic begins to soften above 160F.
Used for exterior and interior windows, doors, skylights, clerestories and greenhouse glazing, acrylic sheets can be moulded into various shapes and contours. Both single-skin and double-skin versions of the material are available. Single-skin acrylic is clear and comes in sheets or continuous rolls of various thicknesses. Extruded into a hollow-walled sheet material, double-skin acrylic has interior ribs, spaced 5/8 in. apart, running the length of the sheet. It is translucent, but not transparent.
The Debate
Builders and designers who have worked with acrylic fall into two camps: they either hate it or love it. Any type of glazing is ultimately compared with glass, and those who like acrylic, whether single or double shin, offer these reasons:
It is versatile. Single-skin acrylic can be cut into a multiplicity of shapes, either for pure design reasons or to meet the demands of an out-of-square solar retrofit. Single-skin acrylic can be cold-formed into curves; both single and double-skin sheets can be heat-formed.
Acrylics are easy to cut and can be site-fabricated. Lighter in weight and easier to carry, the double-skin sheet is more convenient to install than glass. The flexibility of single-skin sheets varies with their thickness; longer sheets of thinner acrylic require more people to handle them.
Acrylic has high transmissivity, and better impact strength than glass. Double-skin acrylic has an R-value competitive with insulated glass units. It is safe in overhead applications, because it will not shatter. Instead it breaks into large, dull-edged pieces.
On the other hand, builders who prefer glass offer these reasons: Acrylic has a high rate of expansion and contraction, requiring careful attention to keep an installation leak-proof. As it moves, the acrylic sheet makes a noise described as ticking or cracking and acrylic scratches easily. The extent, to which this is considered a problem, or even an annoyance, varies from builder to builder.
Costs
Acrylic used to be much cheaper than glass, but now single-skin acrylic is competitive only when purchased in bulk. Any cost advantage is likely to be lost if you attempt to double-glaze with single-skin acrylic. This is a labour intensive process, and it is tough to eliminate condensation between the panes. The price of double-skin acrylic is close to that of insulated glass, but the cost is higher if the price of a compression fastening system is figured in. (Some builders expect the price of double-skin acrylic to drop in the future when more companies begin to manufacture it.)
If acrylic is used for a roof in a sunspace or greenhouse, however, its availability in assorted lengths can cut down on labour costs. Designer Larry Lindsey, of the Princeton Energy Group, pints out that long pieces eliminate the need for horizontal mullion breaks, and so can be installed less expensively than several smaller ones. They are also cheaper. An uninterrupted piece of glazing can run the full length of the slope, supported by purlins underneath.
Professional use
Architect David Sellers of Sellers & Co., an architectural firm in Warren Vt., explains his extensive use of acrylic: "Our whole plastics experiment has been an aesthetic means of expanding the type of architecture we do. With acrylic we could push the house beyond what it was already, both the inside and the outside experience of it". In the process, the firm has developed a spectrum of applications for single-skin acrylic (sidebar, below right).
Designer-builder Valerie Walsh, of Solar Horizon, Santa Fe, N. Mex., uses double-skin acrylic greenhouses and sunspaces that are her firm’s specialty. She first used single-skin acrylic because it was slick, clean-looking, and did not degrade in the South-western sun. She began to explore unusual shapes, such as a wheel-spoke roof design. Then she turned to using double-skin acrylic. Walsh thermoforms acrylic in her own shop - curved pieces that are as wide as 5½ ft. and typically 6 ft. to 7 ft. long, although she has done 8-footers.
Safety and economics figured prominently in the Princeton Energy Group's decision to use acrylic glazing overhead in their greenhouses and sunspaces.
"The whole issue is a matter of expense," says Larry Lindsay. "In order to have glass products we feel comfortable installing overhead, we have to pay two penalties, one in transmittance and one in bucks. At present, there is no laminated low-iron glass available at a reasonable cost."
For those who have years of experience with acrylic, a willingness to experiment and to learn from mistakes has produced a valuable body of knowledge about working with the material, its design potential and its limits.
Movement
Leaking is a particular concern with acrylic glazing because it moves a lot, expanding and contracting in response to temperature changes. To avoid leaks, design principle number one is to try to eliminate horizontal joints, and yet glazing systems that may do a perfect job of sealing glass joints will not work at all with acrylic. Its movement will pull the caulk right out.
"Acrylic has a tremendous coefficient of expansion - you have to allow maybe an inch over 14 ft. for movement," cautions Chuck Katzenbach, construction manager at PEG where they have worked with double-skin acrylic for exterior applications and single-skin for interior ones. "No silicones or sealants we know of will stretch that potential full inch of movement." Indeed, one builder tells a story about using butyl tape for bedding: The acrylic moved so much in the heat that the tapes eventually dangled from the rafters like snakes.
Room for expansion must be left on all four sides of an acrylic sheet, because the material will expand and contract in all directions. The amount of movement depends on the length of the sheet and the temperature extremes it will be subject to.
Acrylic glazing can be installed year round, but it is vital to pay attention to the temperature when it is put in place. Katzenbach explains that if it is 30 F outside, then you have to remember to allow for expansion to whatever you figure your high temperature will be. If it could go from 30 F to a peak of 120 F in your greenhouse, you have to make provisions for a 90o change.
Cutting
To cut a sheet of acrylic, use a fine-tooth carbide-tipped blade set for a shallow cut, and move like a snail. This is important because speed will cause little pressure cracks to appear on the bottom edge. While cutting, make sure that the sheet is firmly supported on both sides of the cut. Sharpness is vital, so use that blade only for working with acrylic. When the acrylic is cut it heats up and the edges melt, but the wider kerf of a carbide blade will prevent the newly cut edges from melting back together again. After the cut, the edges can be planed, filed or sanded.
As the acrylic is cut, little fuzzy pieces will fly up. Some will reglue themselves to the edges and can be broken off when the cutting is completed. With double-skin acrylic, the fuzz tends to fill the 5/8 in. dia. columns between ribs. Use an air gun to blow it out.
If you drill acrylic, support the sheet fully, and use a very sharp spade bit, ground to a sharper angle than for drilling wood. The sharper angle helps prevent cracking. Drill very slowly, and slow down even more just before the drill breaks through the sheet. Be prepared to break some pieces, no matter how careful you are.
Acrylic sheets come protected with an adhesive masking, which exposure to rain or sunlight makes quite difficult to remove. Leave the protective masking on the acrylic as long as possible, and be prepared for a good zap from static electricity when you pull it off.
Fastening
For years it has been common practice to fasten single-skin acrylic by screwing it down. The designers at Sellers & Co. developed a pressure-plate fastening system to distribute the pressure evenly and drilled the holes for the bolts or screws an extra 1/8 in. wide to allow for movement. But after ten years or more, the hole has shifted and started pushing against the screw in some installations. Cracks developed where none had existed.
Small cracks in single-skin acrylic can be stopped if the force on them is not too great. Although his firm now uses installation details that do not involve drilling the sheets, Jim Sanford at Sellers & Co., recommends stopping cracks by drilling a 1/4 in. dia. hole at the end of the crack and filling it with silicone. Designer-builder Alex Wade, of Mt. Marion, N.Y., who still uses screws, suggests drilling a tiny hole at the end of the crack, too. He then widens the crack slightly with a knife and fills it with silicone. Finally, he removes the offending screw. Wade suspects that many builders do not take into account the season of the year in which they are working when they drill the holes for screws. When installing acrylic in the extremes of summer or winter, Wade drives the screw either to the inside or the outside of an over-sized hole in the acrylic, to allow for subsequent contraction or expansion when the temperatures change. It is important to space the holes evenly (about 2 ft. apart) and to tighten the screws uniformly to distribute the pressure equally. The sheet must be held down firmly, but still be able to move.
To avoid taking a chance with cracking, however, most builders have abandoned screw. Instead they use a compression system of battens that hold the plastic sheet down on a smooth bed of ethylene propylene diene monomer (EPDM). It comes in strips and is supplied by several manufacturers. The acrylic can easily slide across the EPDM as it moves.
Manufacturers recommend a 3x rafter to support the bedding in the compression glazing system. PEG installs an interior condensation gutter on greenhouse rafters that doubles as a smooth, uniform bed for the EPDM gasket in the glazing system. The 20-gauge sheet metal straddles the rafter and is bent into a 5/8 in. lip for the gutter on each side.
PEG has also developed a system for a standard 2x. A clear all-heart redwood 1 x 4 trim piece is screwed on top of the 2x, widening the bed and providing a smooth surface (inset drawing, facing page). Concentrated stress on the acrylic sheets is as important to avoid with a compression system as it is with screws. If one point is fastened tighter than the others, the acrylic will bow in and leak or crack.
Larry Lindsey recommends aluminium battens on south-facing roofs, because wooden ones will eventually cup upward, creating a leak. Aluminium battens can be purchased with various finishes, or they can be capped with a strip of red wood.
Double-skin acrylic needs to be supported at its base or it will bow instead of moving within the compression glazing system.
PEG lets the sheets hang over the roof's edges as a shingle would sealing it underneath. For the bottom edge on installations with curved roofs, Valerie Walsh has developed a system with no damming problems. She slides on aluminium terminal section (ATS) from CYRO on the bottom of the double-skin acrylic, then snugs the acrylic into a larger aluminium U-channel that is in turn screwed into the wood beam. Walsh then caulks the inside and rills weep holes through the outside of the U-channel.
In one of his designs, David Sellers decided to glaze the south-facing roof area with long strips of single-skin acrylic. To avoid leaking, he encouraged the tendency of the 1/4 in. sheets to sag slightly. Small blocks under the edges of the sheets accentuate the dip. Melting snow or rain flows to the center of each panel and then drains off the roof. On the bottom edge, an angle keeps the acrylic from slipping.
Glazing materials
Acrylic is fussy stuff. Chuck Katzenbach reels off a list of materials to avoid using with this plastic. Vinyl leaches into acrylic and weakens its edges. Some butyls have plasticizers that may also leach into acrylic. In these cases, either the acrylic will eventually fail or the butyl will become very hard. The plasticizer in most neoprenes is not compatible, so check with the manufacturer.
Compatible glazing materials are few: EPDM heads the list. Silicone caulk is okay, but sooner or later the acrylic's movement will pull it loose. If it is installed on a cold day, the silicone may pull out on the first really warm one. There are many urethane foams you can use, but you would be well advised to consult the manufacturer directly about compatibility.
Support
The double-skin acrylic can bow in over the length of the roof, and the sheet could conceivably pull out of the glazing system under a very heavy snow load, according to Larry Lindsey. So as a cautionary measure, PEG figures on a 30-lb. snow load and installs purlins 4 ft. o.c., about 5/8 in. below the sheet.
Condensation
Acrylic transpires water vapour, so a double-skin unit typically will have some cloudy vapour inside. Double-skin acrylic should be installed with its ribs running down the slope so that any condensation inside the channels will collect at the bottom edge of the sheet. This edge needs to be vented. Double-skin sheets arrive with rubber packing material in both ends of the channels, to keep them free of debris. PEG's construction crew just leaves it there and perforates it with a scratch awl to allow air movement.
Cleaning
Never use abrasives, ammonia-base glass cleaners or paint thinner on acrylic glazing. Mild detergent, rubbing alcohol, turpentine and wax-base cleaner-polishers designed especially for plastic are safe when applied with a soft cloth.
Cleaning brings up the controversial issue of scratching. "The scratching drives me crazy, though other builders do not seem to care as much," says Valerie Walsh. Whether she is storing the sheets she has heat-formed into curves or transporting them to the building site, she keeps thin sheets of foam padding wrapped around every piece.
"With double-skin acrylic, people's tendency is not to expect to be able to see through it. They are not looking through it as they would through a window, and so they are not seeing the small imperfections in the surface itself," argues Chuck Katzenbach.
Even though single-skin acrylic is transparent, many builders who work with it say that scratching just is not a significant problem, particularly if the glazing is kept clean. The only serious scratching problem is likely to be the work of a dog. Most scratches can be easily removed with a Simonize paste-wax buffing. And now some single-skin acrylics are available with a polysilicate coating that makes them abrasion-resistant and also improves their chemical resistance.
Commonplace now as the stuff of automobile lights, bank security window, gas-station signs, camera and contact lenses, TV screens, and even paint, blankets and carpets, acrylic plastic has been around a long time. Although development of this highly elastic substance began back in the 19th century, it was not until the 1930s that chemical firms first began producing commercial quantities of acrylic, which can be manufactured as a liquid, as fibres or in sheets. It took World War II, when the War Department started testing and using acrylic extensively in aircraft, to push the technology into the applications familiar to us today.
The larger family of plastic glazing materials has been closely scrutinized over the last decade by solar designers and builders searching for the least expensive material for collectors, greenhouses, windows, skylights and water storage. Most plastic glazings are flexible, light-weight, impact-resistant and light-diffusing. Acrylic stands out because it will not degrade or yellow in ultraviolet light. Along with high clarity and an impact resistance of 15 to 30 times greater than that of glass, acrylic offers a lifetime gauged at 20 years.
Given a burning rate of Class II in the codes, acrylic burns very rapidly, but does not smoke or produce gases more toxic than those produced by wood or paper. The ignition temperature is higher than that of most woods, but acrylic begins to soften above 160F.
Used for exterior and interior windows, doors, skylights, clerestories and greenhouse glazing, acrylic sheets can be moulded into various shapes and contours. Both single-skin and double-skin versions of the material are available. Single-skin acrylic is clear and comes in sheets or continuous rolls of various thicknesses. Extruded into a hollow-walled sheet material, double-skin acrylic has interior ribs, spaced 5/8 in. apart, running the length of the sheet. It is translucent, but not transparent.
The Debate
Builders and designers who have worked with acrylic fall into two camps: they either hate it or love it. Any type of glazing is ultimately compared with glass, and those who like acrylic, whether single or double shin, offer these reasons:
It is versatile. Single-skin acrylic can be cut into a multiplicity of shapes, either for pure design reasons or to meet the demands of an out-of-square solar retrofit. Single-skin acrylic can be cold-formed into curves; both single and double-skin sheets can be heat-formed.
Acrylics are easy to cut and can be site-fabricated. Lighter in weight and easier to carry, the double-skin sheet is more convenient to install than glass. The flexibility of single-skin sheets varies with their thickness; longer sheets of thinner acrylic require more people to handle them.
Acrylic has high transmissivity, and better impact strength than glass. Double-skin acrylic has an R-value competitive with insulated glass units. It is safe in overhead applications, because it will not shatter. Instead it breaks into large, dull-edged pieces.
On the other hand, builders who prefer glass offer these reasons: Acrylic has a high rate of expansion and contraction, requiring careful attention to keep an installation leak-proof. As it moves, the acrylic sheet makes a noise described as ticking or cracking and acrylic scratches easily. The extent, to which this is considered a problem, or even an annoyance, varies from builder to builder.
Costs
Acrylic used to be much cheaper than glass, but now single-skin acrylic is competitive only when purchased in bulk. Any cost advantage is likely to be lost if you attempt to double-glaze with single-skin acrylic. This is a labour intensive process, and it is tough to eliminate condensation between the panes. The price of double-skin acrylic is close to that of insulated glass, but the cost is higher if the price of a compression fastening system is figured in. (Some builders expect the price of double-skin acrylic to drop in the future when more companies begin to manufacture it.)
If acrylic is used for a roof in a sunspace or greenhouse, however, its availability in assorted lengths can cut down on labour costs. Designer Larry Lindsey, of the Princeton Energy Group, pints out that long pieces eliminate the need for horizontal mullion breaks, and so can be installed less expensively than several smaller ones. They are also cheaper. An uninterrupted piece of glazing can run the full length of the slope, supported by purlins underneath.
Professional use
Architect David Sellers of Sellers & Co., an architectural firm in Warren Vt., explains his extensive use of acrylic: "Our whole plastics experiment has been an aesthetic means of expanding the type of architecture we do. With acrylic we could push the house beyond what it was already, both the inside and the outside experience of it". In the process, the firm has developed a spectrum of applications for single-skin acrylic (sidebar, below right).
Designer-builder Valerie Walsh, of Solar Horizon, Santa Fe, N. Mex., uses double-skin acrylic greenhouses and sunspaces that are her firm’s specialty. She first used single-skin acrylic because it was slick, clean-looking, and did not degrade in the South-western sun. She began to explore unusual shapes, such as a wheel-spoke roof design. Then she turned to using double-skin acrylic. Walsh thermoforms acrylic in her own shop - curved pieces that are as wide as 5½ ft. and typically 6 ft. to 7 ft. long, although she has done 8-footers.
Safety and economics figured prominently in the Princeton Energy Group's decision to use acrylic glazing overhead in their greenhouses and sunspaces.
"The whole issue is a matter of expense," says Larry Lindsay. "In order to have glass products we feel comfortable installing overhead, we have to pay two penalties, one in transmittance and one in bucks. At present, there is no laminated low-iron glass available at a reasonable cost."
For those who have years of experience with acrylic, a willingness to experiment and to learn from mistakes has produced a valuable body of knowledge about working with the material, its design potential and its limits.
Movement
Leaking is a particular concern with acrylic glazing because it moves a lot, expanding and contracting in response to temperature changes. To avoid leaks, design principle number one is to try to eliminate horizontal joints, and yet glazing systems that may do a perfect job of sealing glass joints will not work at all with acrylic. Its movement will pull the caulk right out.
"Acrylic has a tremendous coefficient of expansion - you have to allow maybe an inch over 14 ft. for movement," cautions Chuck Katzenbach, construction manager at PEG where they have worked with double-skin acrylic for exterior applications and single-skin for interior ones. "No silicones or sealants we know of will stretch that potential full inch of movement." Indeed, one builder tells a story about using butyl tape for bedding: The acrylic moved so much in the heat that the tapes eventually dangled from the rafters like snakes.
Room for expansion must be left on all four sides of an acrylic sheet, because the material will expand and contract in all directions. The amount of movement depends on the length of the sheet and the temperature extremes it will be subject to.
Acrylic glazing can be installed year round, but it is vital to pay attention to the temperature when it is put in place. Katzenbach explains that if it is 30 F outside, then you have to remember to allow for expansion to whatever you figure your high temperature will be. If it could go from 30 F to a peak of 120 F in your greenhouse, you have to make provisions for a 90o change.
Cutting
To cut a sheet of acrylic, use a fine-tooth carbide-tipped blade set for a shallow cut, and move like a snail. This is important because speed will cause little pressure cracks to appear on the bottom edge. While cutting, make sure that the sheet is firmly supported on both sides of the cut. Sharpness is vital, so use that blade only for working with acrylic. When the acrylic is cut it heats up and the edges melt, but the wider kerf of a carbide blade will prevent the newly cut edges from melting back together again. After the cut, the edges can be planed, filed or sanded.
As the acrylic is cut, little fuzzy pieces will fly up. Some will reglue themselves to the edges and can be broken off when the cutting is completed. With double-skin acrylic, the fuzz tends to fill the 5/8 in. dia. columns between ribs. Use an air gun to blow it out.
If you drill acrylic, support the sheet fully, and use a very sharp spade bit, ground to a sharper angle than for drilling wood. The sharper angle helps prevent cracking. Drill very slowly, and slow down even more just before the drill breaks through the sheet. Be prepared to break some pieces, no matter how careful you are.
Acrylic sheets come protected with an adhesive masking, which exposure to rain or sunlight makes quite difficult to remove. Leave the protective masking on the acrylic as long as possible, and be prepared for a good zap from static electricity when you pull it off.
Fastening
For years it has been common practice to fasten single-skin acrylic by screwing it down. The designers at Sellers & Co. developed a pressure-plate fastening system to distribute the pressure evenly and drilled the holes for the bolts or screws an extra 1/8 in. wide to allow for movement. But after ten years or more, the hole has shifted and started pushing against the screw in some installations. Cracks developed where none had existed.
Small cracks in single-skin acrylic can be stopped if the force on them is not too great. Although his firm now uses installation details that do not involve drilling the sheets, Jim Sanford at Sellers & Co., recommends stopping cracks by drilling a 1/4 in. dia. hole at the end of the crack and filling it with silicone. Designer-builder Alex Wade, of Mt. Marion, N.Y., who still uses screws, suggests drilling a tiny hole at the end of the crack, too. He then widens the crack slightly with a knife and fills it with silicone. Finally, he removes the offending screw. Wade suspects that many builders do not take into account the season of the year in which they are working when they drill the holes for screws. When installing acrylic in the extremes of summer or winter, Wade drives the screw either to the inside or the outside of an over-sized hole in the acrylic, to allow for subsequent contraction or expansion when the temperatures change. It is important to space the holes evenly (about 2 ft. apart) and to tighten the screws uniformly to distribute the pressure equally. The sheet must be held down firmly, but still be able to move.
To avoid taking a chance with cracking, however, most builders have abandoned screw. Instead they use a compression system of battens that hold the plastic sheet down on a smooth bed of ethylene propylene diene monomer (EPDM). It comes in strips and is supplied by several manufacturers. The acrylic can easily slide across the EPDM as it moves.
Manufacturers recommend a 3x rafter to support the bedding in the compression glazing system. PEG installs an interior condensation gutter on greenhouse rafters that doubles as a smooth, uniform bed for the EPDM gasket in the glazing system. The 20-gauge sheet metal straddles the rafter and is bent into a 5/8 in. lip for the gutter on each side.
PEG has also developed a system for a standard 2x. A clear all-heart redwood 1 x 4 trim piece is screwed on top of the 2x, widening the bed and providing a smooth surface (inset drawing, facing page). Concentrated stress on the acrylic sheets is as important to avoid with a compression system as it is with screws. If one point is fastened tighter than the others, the acrylic will bow in and leak or crack.
Larry Lindsey recommends aluminium battens on south-facing roofs, because wooden ones will eventually cup upward, creating a leak. Aluminium battens can be purchased with various finishes, or they can be capped with a strip of red wood.
Double-skin acrylic needs to be supported at its base or it will bow instead of moving within the compression glazing system.
PEG lets the sheets hang over the roof's edges as a shingle would sealing it underneath. For the bottom edge on installations with curved roofs, Valerie Walsh has developed a system with no damming problems. She slides on aluminium terminal section (ATS) from CYRO on the bottom of the double-skin acrylic, then snugs the acrylic into a larger aluminium U-channel that is in turn screwed into the wood beam. Walsh then caulks the inside and rills weep holes through the outside of the U-channel.
In one of his designs, David Sellers decided to glaze the south-facing roof area with long strips of single-skin acrylic. To avoid leaking, he encouraged the tendency of the 1/4 in. sheets to sag slightly. Small blocks under the edges of the sheets accentuate the dip. Melting snow or rain flows to the center of each panel and then drains off the roof. On the bottom edge, an angle keeps the acrylic from slipping.
Glazing materials
Acrylic is fussy stuff. Chuck Katzenbach reels off a list of materials to avoid using with this plastic. Vinyl leaches into acrylic and weakens its edges. Some butyls have plasticizers that may also leach into acrylic. In these cases, either the acrylic will eventually fail or the butyl will become very hard. The plasticizer in most neoprenes is not compatible, so check with the manufacturer.
Compatible glazing materials are few: EPDM heads the list. Silicone caulk is okay, but sooner or later the acrylic's movement will pull it loose. If it is installed on a cold day, the silicone may pull out on the first really warm one. There are many urethane foams you can use, but you would be well advised to consult the manufacturer directly about compatibility.
Support
The double-skin acrylic can bow in over the length of the roof, and the sheet could conceivably pull out of the glazing system under a very heavy snow load, according to Larry Lindsey. So as a cautionary measure, PEG figures on a 30-lb. snow load and installs purlins 4 ft. o.c., about 5/8 in. below the sheet.
Condensation
Acrylic transpires water vapour, so a double-skin unit typically will have some cloudy vapour inside. Double-skin acrylic should be installed with its ribs running down the slope so that any condensation inside the channels will collect at the bottom edge of the sheet. This edge needs to be vented. Double-skin sheets arrive with rubber packing material in both ends of the channels, to keep them free of debris. PEG's construction crew just leaves it there and perforates it with a scratch awl to allow air movement.
Cleaning
Never use abrasives, ammonia-base glass cleaners or paint thinner on acrylic glazing. Mild detergent, rubbing alcohol, turpentine and wax-base cleaner-polishers designed especially for plastic are safe when applied with a soft cloth.
Cleaning brings up the controversial issue of scratching. "The scratching drives me crazy, though other builders do not seem to care as much," says Valerie Walsh. Whether she is storing the sheets she has heat-formed into curves or transporting them to the building site, she keeps thin sheets of foam padding wrapped around every piece.
"With double-skin acrylic, people's tendency is not to expect to be able to see through it. They are not looking through it as they would through a window, and so they are not seeing the small imperfections in the surface itself," argues Chuck Katzenbach.
Even though single-skin acrylic is transparent, many builders who work with it say that scratching just is not a significant problem, particularly if the glazing is kept clean. The only serious scratching problem is likely to be the work of a dog. Most scratches can be easily removed with a Simonize paste-wax buffing. And now some single-skin acrylics are available with a polysilicate coating that makes them abrasion-resistant and also improves their chemical resistance.
Tuesday, September 4, 2007
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Monday, September 3, 2007
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Sports
News
Movies
Music
Weather
Kids Channels
Educational
Shopping
Clips
+ Radio Stations and much, much more!
You can also watch the Big Games LIVE without any additional fee or subscription!
Tired of missing the Big Game because your cable company doesn't carry it?
Are you a sports fan who wants LIVE coverage daily? With this offer you are likely to be satisfied by the large range of events/games covered by our network.
Stop paying for high-priced cable or Satellite services! Watch LIVE Games (even the games that are not shown elsewhere) - with our software!
--------------------------------------------------------------------------------
Watch TV in English, Spanish, German, Arabic, French, Italian, Russian, Dutch and more!
You may also browse world TV by regions or by country name.
FOR EXAMPLE YOU WILL GET STATIONS FROM THE FOLLOWING COUNTRIES:
ALBANIA
ALGERIA
ANDORRA
ARGENTINA
AUSTRALIA
AUSTRIA
BELARUS
BELGIUM
BOLIVIA
BOSNIA
BRAZIL
CANADA
CHILE
CHINA
COLOMBIA
COSTA RICA
CUBA
CZECH REP
DENMARK
DOMINIC. REP
EGYPT
ESTONIA
FINLAND
FRANCE
GERMANY
GREECE
HUNGARY
ICELAND
INDIA
INDONESIA
IRAN
IRAQ
ISRAEL
ITALY
JAMAICA
JAPAN
JORDAN
KURDISTAN
KUWAIT
LATVIA
LEBANON
LUXEMBURG
MACEDONIA
MALAYSIA
MALTA
MEXICO
MONGOLIA
NETHERLANDS
NEW ZEALAND
NICARAGUA
NIGERIA
OMAN
PANAMA
PERU
PHILIPPINES
POLAND
PORTUGAL
PUERTO RICO
QATAR
ROMANIA
RUSSIAN FED
SAUDI ARABIA
SERBIA
SOUTH AFRICA
SOUTH KOREA
SPAIN
SRI LANKA
SWEDEN
SWITZERLAND
TAIWAN
THAILAND
TURKEY
UNITED KINGDOM
UKRAINE
USA
VATICAN CITY
VENEZUELA
VIETNAM
+PLUS MUCH MORE!!!
*THIS HUGE SELECTION IS NOT FOUND ANYWHERE ELSE*
--------------------------------------------------------------------------------
BENEFITS:
PERFECTLY LEGAL: 100% Legal - No hacking or cracking!
IT WORKS ANYWHERE IN THE WORLD: U.S., U.K., Canada, Japan, India, Russia, etc. Connect To A Whole New World Of Online Entertainment.
NO EXTRA HARDWARE OR TV CARD REQUIRED: There is no need to buy extra hardware equipment or a PC TV card because the TV channels are streamed through your internet connection. You just need an internet connection (the faster your internet speed the better picture you will get). It even works with a 56k connection. (A Broadband connection will deliver superior audio and video quality).
VERY EASY TO USE / NO PC KNOWLEDGE REQUIRED: Just install the program and click - then instantly watch International satellite channels on your PC! It only takes a few seconds...
NO SUBSCRIPTIONS NEEDED & NO RECURRING CHARGES... EVER! Get all the entertainment you need for a one time payment of only $99.95!
NO ADS OR SPYWARE!
WORKS WITH ALL VERSIONS OF WINDOWS (95, 98, NT, ME, 2000, XP)
THERE ARE NO CATCHES AND THERE IS NOTHING EXTRA TO PAY... EVER!
--------------------------------------------------------------------------------
Get over 4000 Stations for a small one-time fee.
Once you have bought the software, you have nothing else to pay... EVER!
You won't be disappointed...
Just visit the following site and see more details...
http://4ernesto.satsoft.hop.clickbank.net/
Sunday, September 2, 2007
SysFixMaster...
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